A series of experiments that were conducted to evaluate the relative merits of three types of diversities in the indoor portable radio channels at 900 MHz is described. Unmodulated tones were used to probe the channel in a typical university work environment. The statistics of the signal envelopes were analyzed to determine the correlation of the field strengths when the signals are separated in space, frequency or polarization. According to the results presented here, the perforOf a narrow-band system ( < 2oo kHz) at 900 MHz greatly benefit from a frequency diversity scheme provided that the separation between the two frequencies is greater than approximately 5 MHz. Similarly, the advantage of space diversity is found significant when the two antennas are spaced by 3/4 wavelength or more. It is also reported that co-polarized and cross-polarized signals are nearly uncorrelated and their relative field strengths differ by less than 2 dB in most locations.specifically at obtaining parameters pertaining to different diversity schemes. ~~f i~~~ and cox [71 and cox, M~~~~~, and Norris 181 used continuous wave (CW) signals to investigate the radio coverage inside a building when the transmitter was placed outside. Alexander [9], [IO] was one of the first to report on truly indoor propagation measurements. He used CW signals to probe the channel on one floor, where both the transmitter and receiver were placed in locations inside the buildi%. A h a n d e r and I1 l1 used a two-branch space diversity receiver with selection combining to see the possible improvements in the signal envelope. Patsiokas et al. 1121 performed indoor attenuation measurements at several frequencies using cw There have also been several reports on experimental data in papers devoted primarily to system studies. In all these studies, however, there has been little results that directly address the question of parameters from the impulse response measurements, but that the results and the In Section II a description of our experiment is given, followed by a presentation of the results in Section 111, and conclusions in Section Iv. THE EXPERIMENT